The general working principle of supercritical fluid extraction device is to make use of the relationship between the supercritical fluid's dissolution capacity and its density, and also the influence of pressure and temperature on the supercritical fluid. In supercritical fluid extraction unit, the supercritical fluid is contacted with the substances to be separated, so that it selectively extracts the components of polarity, boiling point and molecular weight. Moreover, the extract obtained by temperature and pressure corresponding to various conditions can not make single, but controlled conditions obtain the best proportion of the mixed components. Then the supercritical fluid into ordinary gas by means of vacuum and heating, so after processing the supercritical extraction device, extraction material completely or basically precipitated, so as to achieve the purpose of purification separation process, so the supercritical extraction device is composed of extraction and separation process of assembly. Supercritical C02 refers to a critical temperature and critical pressure (called critical point) of a compressible fluid above the high density state, is usually talking about chemistry except the gas liquid solid three states in fourth states, the intermolecular force is small, similar to the other, and the density is great therefore, close to the liquid, with liquid between gas and liquid two properties, and liquidity have dissolved and gas, its mass transfer rate is much higher than the ordinary liquid, and the diffusion coefficient between liquid and gas, has good penetration ability.
The traditional separation method used in supercritical fluid extraction refers to the extraction by using the compatibility between solvents and solutes, that is, the different solubility. Distillation is achieved by the different volatile components of solvents. Compared with the above method, the extraction method is advanced by adjusting the C02 pressure and temperature to control the solubility and vapor pressure of the 2 parameters were extracted, so advanced supercritical extraction device integrates two functions and characteristics of solvent extraction and distillation, and then determine the advantages and process of supercritical C02 extraction has the conventional extraction methods have no: by controlling the pressure and temperature conveniently and rapidly change the nature of the solvent control, choose extracted substances; proper extraction and solvent, capable of operating at close to room temperature, suitable for heat sensitive material.